Toilet Thetford C250, which reed switch? Single or multi level?

[ALTUS]

Hi
I have to buy reed switch, but I don't know which is proper for my toilet? When I bought my caravan, there was not that plate. Both of them have the same (I suppose) electrical contacts.
Control panel has only buton and one control light. I wonder how it works, because I can not find information. Is it changing colour, yellow -half level, red - full? Which one should I buy?

My command centre

Regards

 

[otherclive]

Mine went from Off to Red without any intermediate colour. But rarely did we let it go to Red, preferring a routine of regular daily emptying.

 

[ALTUS]

Mine went from Off to Red without any intermediate colour. But rarely did we let it go to Red, preferring a routine of regular daily emptying.

It seems that I should to buy single level switch. Maybe there are other types of displays with more control lights. Thanks for info.